TW200816507A - Method for texturing silicon wafers for producing solar cells - Google Patents

Abstract

In a method for texturing silicon wafers for producing solar cells, the step of introducing a silicon wafer makes use of a texturing solution which is at a temperature of at least 80 degrees Celsius and which comprises water admixed with 1 percent by weight to 6 percent by weight of KOH or 2 percent by weight to 8 percent by weight of NaOH and with a surfactant or a surfactant mixture with less than 0.01 percent by weight. Very economic texturing can be carried out as a result.

Description

200816507 IX. Description of the Invention: [Technical Field of the Invention] The present invention relates to a method of engraving wafers for manufacturing solar cells. [Prior Art] A method of fabricating a solar cell wafer is described, for example, in DE 698 1 1 511 T2. The method deposits the germanium wafer into a embossed solution containing water, 0.1 to 8 weight percent NaOH or 3 to 6 weight percent ,0 ,, an assay solution and a surfactant (Nippon 0il and Fat c〇) The product of mpany, Ltd., Sintrex, preferably has a surfactant of more than 1% by weight. The surfactant can be replaced by isopropanol, where the engraving is usually carried out at a temperature of 85 °C. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a solar cell wafer, which is economical. It is an object of the present invention to provide a method for fabricating a solar cell wafer in which a temperature of the engraved solution is at least 8 (TC, and the engraving is performed in the step of placing the germanium wafer in the engraving solution. The solution consists of water plus 1 to 6 weight percent Κ0 Η or 2 to 8 weight percent NaOH and less than 〇· 〇1 weight percent of surfactant or surfactant mixture. The embossing solution of the present invention contains no other ingredients or additives. The concentration of the surfactant or surfactant in the present invention is extremely low, so that unfavorable characteristics do not occur at a higher process temperature, such as foam generation, and a relatively high knurling speed can be achieved, and the embossing has a high economical efficiency. In one embodiment of the invention, the embossing solution contains less than 5% by weight of ΠΧΡ3发明/invention specification (supplement)/96-11/96129322 5 200816507 ratio of surfactant or surfactant mixture. In another embodiment of the present invention, the concentration of the surfactant is less than 〇·001 by weight. The concentration of Κ0Η is preferably from 3 to 5 by weight of the surfactant or surfactant mixed to 4 to 6 weight percent. The concentration of NaOH is preferably 'particularly 95 ° C, especially the temperature to the embossing solution is preferably 90 ° C and 97 ° C. The following description will be made in detail based on examples. [Embodiment] Fig. 1 shows a method of processing a wafer according to an embodiment of the method of the present invention. Ingot is sawed into a plurality of germanium wafers 3 in a cutting station 2. The method of the present invention makes Shi Xi The wafer 3 is stacked in a wafer 5 at a scribing station 4, and the 5 liter wafer rack 5 is placed in the engraving solution container 6. The engraved solution container 6 is provided with a embossing solution 7, so that The Shixi wafer 3 is completely immersed in the engraving solution 7. The temperature of the engraved solution 7 is measured by a temperature in contact with it. The sensor 8 measures the heating element whose temperature is also immersed in the engraving solution 7. 9. Effect: An orifice plate 10 is disposed between the heating element 9 and the wafer holder 5. After the engraving station 4 completes the method of the present invention, the crucible wafer 3 is conveyed to a diffusion station 11 for further processing of solar cell manufacturing. All of the embossings used in the following examples use semiconductor grades.

All of the following examples were performed using a single crystal germanium wafer manufactured by the manufacturer M. Setek ((100-Cz, as-cut, p-Type (B〇r), 125 min>< 125 mm, 150 mm in thickness, 300 pm) or Deutsche Solar's single crystal 312XP / invention specification (supplement) / 96-11/96129322 6 200816507 矽 wafer (0. 5-1. 7 Ohm. cm). The wafer is maintained in a diced state and the dicing damage is not removed, but the ruthenium wafer can also be etched or otherwise processed prior to performing the method of the present invention. The fluctuation of the reflection value as the characteristic value of the photo-generated voltage conversion efficiency is generally about 1% absolute value. (Concentrated dishwashing re Re ny) This example uses a concentrated dishwashing detergent for household use (trade name Reiny) containing less than 5 weight percent of nonionic surfactant, amphoteric surfactant and South 3 0 A percentage by weight of anionic surfactant. The other parameters and results of this example are as follows: Table 1 (concentrated dishwashing Re ny) surfactant percentage by weight % K0H weight percent % temperature °c time min reflection % no 2 « 98 10 16 6 0.001 3 « « 98 10 11.4~ As shown in Table 1, the reflection of the control group without surfactant was higher than that of the experimental group using 001 weight percent concentrated dishwashing detergent. This extremely low boundary I surfactant or surfactant mixture concentration has a significant effect on improving the photo-generated voltage conversion efficiency. The reflection value can be less than 丨3%, especially less than 125% 〇 (Cleaner M14) This addition is made using the German Fleet manufacturer Marf丨^ & Co

The Ml 4 cleaner acts as a surfactant mixture comprising from 5 to 15 weight percent of anionic surfactant, nonionic surfactant, preservative and amide. 3UXP/Invention Manual (supplement)/96-11/96129322 7 200816507

This example uses the cation of the I Goldschmidt PA127A0077, the early A, the soil, the main sparse, n. t. ^ Amm〇nyx L〇 (Lauryl-Myristyl

Dimethylaminoxide secondary 飧 '六 . & life liquid, 30.1 % Dodecyl

Dimethylaminoxide) as 昃;,工^邛马 surfactant or surfactant mixture 0 Table 3 (AL0) Surfactant wt%% ΐΓ0ΐΓ~^^ __重百#_1卜.〇/〇temperature—~C_I time Min reflection % 0. 002 -------«IV/0 0.0035 广10 13. 3 0. 005 __J7-98 97-qq 20 12. 2 ethoxylated fatty alcohol of the type produced by AG) Use of Essen Goldschmidt ES993200616 non-ionic Ec丨 (end-end closure 312XP / invention specification (supplement) / 96-11/96129322 8 200816507 as a surfactant or exhibit and surfactant 4 (TEC)

(REW0) This example uses amphoteric Rew〇teric am 2 C NM (N-cocoate-aminoethyl-N-(2-hydroxyethyl)glycine 4%% produced by Essen Goldschmidt AG, model ST04219293 The aqueous solution, sodium salt) acts as a surfactant or a mixture of surfactants. 9 312XP/Invention Manual (supplement)/96·11/96129322 200816507 Table 5 (REWO) Surfactant Weight % K0H Weight % % Temperature °C Time min Reflection % 0.0002 2 97-98 20 12.3 0.0005 2 97-98 20 12 4 0. 0010 2 97-98 20 12. 4 0. 0015 2 97 - 98 20 119 0.0020 3 97 - 98 20 12.4 (TDO) This example uses the positive Tegotens DO of model PA03500400 produced by Essen Goldschmidt AG ( Alkyldimethylaminoxide aqueous solution, 29.9% 〇6〇71 (1丨11161; 1^1&111丨11〇^丨(16) as a surfactant or surfactant mixture. Table 6 (TD0)

The reduction in the degree of 0.005 wt% is particularly noticeable, and the value of ',' has been reached after 1Q minutes of the engraving time. Acceptable (TD0 control group) DE 698 11 511 T2 The surfactant concentration is close to the lowest value. Refer to the control group of 312XP/Invention Manual (Supplement)/9641/96129322 10 200816507 for the use of the above surfactant TD〇. Table: Table 7 (TD0 control group)

—" ! Reflection # 1 % 12· 2 21.4 26. 6 As shown in Table 7, the surfactant concentration increased to 〇·5 weight percent = and the reflection increased to an unacceptable value. At elevated temperatures, this high concentration can result in extremely unfavorable foam formation that cannot be controlled by process technology. The surfactant concentration of the present invention is only one tenth of the surfactant range of DE 698 1 1 51 1 Τ2. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of the method of the present invention. [Main component symbol description] 1 second crystal block 2 cutting station

V 4 5 6 7 8 9 10 11 3 sec wafer engraving station wafer holder engraving solution container engraving solution temperature sensor heating element orifice diffusion station 312 ΧΡ / invention manual (supplement) / 96-11/96129322 11

Claims (1)

200816507 X. Apply for a patent Fan Park··1. A method of fabricating a solar cell dream wafer engraving, comprising the step of placing a scorpion scorpion into a embossing solution, the temperature of the embossing solution being at least 80 C 'sub-water added; [to 6 wt% 丽Or 2 to 8 weight percent NaOH and a surfactant mixture or surfactant mixture of less than 〇·〇1. 2. For the method of applying the patent range μ, 纟, engraved on the boundary of 0.005 wt% 仗 3 low r _ . ^ ^ back, ancient ^ or surfactant mixture. 3) If the scope of the patent application scope is the first item in 0 001 番旦百八^, /, the engraved solution contains low, · 百里比比比比 surfactant or interface, &丨; 丨 A 4 w and surfactant mixture. • 4· 々曱 专利 专利 专利 专利 专利 专利 专利 专利 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、彳八, • 5· As claimed in any of claims 1 to 3, the embossing solution contains 4 to 6 weight percent of Na〇H. / , ,, 6· The temperature of the embossing solution is at least 9 如 as claimed in any one of claims 1-5. Hey. The method, wherein the temperature of the engraved solution is at least 9.5, as claimed in any one of claims 1 to 5. Hey. 8. In the case of any of claims 1 to 5, the temperature of the engraved solution is at least 9 7 °c. Method 312XP/Invention Manual (supplement)/96-11/96129322 12